ava has no default export.

[mesqueeb]

Please provide details about:

• What you're trying to do

Based on a recent blog post of Sindresorhus I'm trying to convert my most low level npm package to node 12.
I changed the package.json to

"type": "module",
"exports": "./dist/index.js",
"engines": { "node": ">=12.13" },

• What happened

Ever since this I cannot execute Ava tests. I get this error:

test/ava.ts(1,8): error TS1192: Module '"/Users/lucaban/ghq/github.com/mesqueeb/is-what/test/ava"' has no default export.

• What you expected to happen

No error.

Here is my repo:

https://github.com/mesqueeb/is-what/tree/esm

See the esm branch ↑

Also, this is the Ava config:

"ava": {
    "extensions": [
      "ts"
    ],
    "require": [
      "tsconfig-paths/register",
      "ts-node/register"
    ]
  },

I know there are so many recourses about ESM, but it's come to a point where everyone is saying different things and I can't seem to figure out exactly what I'm doing wrong.

If someone can point me into the correct direction, that would be great!

[novemberborn]

Looking at the configuration you've shared here, AVA must be treating the test file as CJS. This feels like a TypeScript compilation issue to me, to do with compatibility between the module formats. Try compiling the code directly and see if that gives you better clues.

We're looking to make some changes here as part of the AVA 4 work.

[mesqueeb]

@cspotcode thank you for the insight. After adding "moduleResolution": "node" to my tsconfig, I get a different error:

  /Users/lucaban/ghq/github.com/mesqueeb/is-what/test/ava.ts:1
  import test from 'ava';
  ^^^^^^

  SyntaxError: Cannot use import statement outside a module

  › SyntaxError: Cannot use import statement outside a module
  › Module.m._compile (node_modules/ts-node/src/index.ts:1056:23)
  › require.extensions.<computed> (node_modules/ts-node/src/index.ts:1059:12)

Do you have any next advice for me? : )
Much appreciated!!

PS: the package is here: https://github.com/mesqueeb/is-what/tree/esm (esm branch)
and the script is npm run test.

[cspotcode]

Node requires you to enable ESM loaders differently than CJS. Explained in their documentation:
https://nodejs.org/dist/latest-v15.x/docs/api/esm.html#esm_loaders

Follow the instructions here:
TypeStrong/ts-node#1007
Be sure you follow them carefully; many people make mistakes and then believe something is broken.

Also consult the working examples in our ava discussion thread:
TypeStrong/ts-node#1247

[mesqueeb]

To anyone coming here, it's easiest to look at these "differences" for setting up Ava tests with TypeScript only:
https://github.com/TypeStrong/ts-node-repros/compare/ava-tests-native-esm

[cspotcode]

May I suggest posting the solution as a new answer and then selecting it?

The problem is that this answer is buried in the "view more" button and may give others the wrong impression. It would be nicer if newcomers to this thread can see the solution right away.

[mesqueeb]

@cspotcode good idea!

[mesqueeb]

To anyone coming here, it's easiest to look at these "differences" for setting up Ava tests with TypeScript only:
https://github.com/TypeStrong/ts-node-repros/compare/ava-tests-native-esm

[novemberborn]

@mesqueeb would you be interested in adding this to our TypeScript recipe?

[mesqueeb]

Sure, how can I help ?

[novemberborn]

I'm thinking we could add an "ES modules with ts-node" section to https://github.com/avajs/ava/blob/main/docs/recipes/typescript.md, and reference that from https://github.com/avajs/ava/blob/main/docs/recipes/es-modules.md?

[mesqueeb]

@novemberborn your wish is my command:
#2701